1. Field of Invention
The present invention relates to an organic electro-luminescence device. More particularly, the present invention relates to an organic electro-luminescence device having a highly transparent, low oxygen and moisture penetrating protective layer.
2. Description of Related Art
Lightweight and high performance displays such as liquid crystal displays are being rapidly developed. However, liquid crystal displays still have some performance problems that need to be tackled, such as a narrow viewing angle, a slow response to signal and a need to have background lighting. Hence, a liquid crystal display is unsuitable for high-speed image animation and wastes a lot of energy powering the background lighting. There is additional difficulty in producing a large liquid crystal display panel.
At present, a new technology for forming a flat panel display capable of addressing all the intrinsic problems of a conventional liquid crystal display has been developed. The new flat panel display is the so-called organic electro-luminescence display (OED). OED is a display device formed using an organic light-emitting material. Each OED device comprises a pair of electrodes and a light-emitting layer. The light-emitting layer contains organic light-emitting material. When an electric current passes between the cathode to the anode of the OED device, light is emitted through the light-emitting mechanism.
Organic electro-luminescence devices may be classified further into organic light emitting diode (OLED) and polymer light emitting diode (PLED). The major difference between the two devices lies in the material application within the light-emitting layer. The light-emitting layer in the organic light emitting diode uses small light-emitting organic molecules. On the other hand, the light-emitting layer in the polymer light emitting diode uses large light-emitting molecules.
In general, an electro-luminescence device is enclosed by a protective layermade from material such as glass, metal, plastic or other high molecular weight polymer. For example, high molecular weight polymer containing fluorine is used in U.S. Pat. No. 5,427,858, the chemical siloxane is used in U.S. Pat. Nos. 5,734,225 and 5,895,228, epoxy resin or polyethylene is used in U.S. Pat. No. 5,811,177, the chemicals polysiloxane, teflon and branching polyolefin are used in U.S. Pat. No. 5,952,778, the chemicals polyvinyl alcohol, polyvinyl acetate derivatives and polyethylene are used in U.S. Pat. No. 6,150,187, the chemicals acrylic polymer, silicon dioxide and silicon carbide are used in U.S. Pat. No. 6,198,217 and diamond shaped carbon, silicon oxide, silicon nitride or metallic material are used in U.S. Pat. No. 6,198,217.
However, if the organic electro-luminescence device has a top emitting structure (in other words, reflective type with light emitting from the anode), the protective layer must have high transparency for visible light. In addition, the protective layer must block out unwanted contaminants such as moisture and oxygen. In brief, the protective layer has to have high transparency and low permeability for moisture and oxygen. So far, none of the aforementioned materials for forming the protective layer has a high light transparency and a low permeability to moisture and oxygen at the same time.
Accordingly, one object of the present invention is to provide an organic electro-luminescence device having a metallocene based cyclic olefin copolymer protective layer such that the protective layer of the electro-luminescence device is highly transparent to light and has a low permeability to both moisture and oxygen.
A second object of this invention is to provides an organic electro-luminescence device having a metallocene based cyclic olefin copolymer substrate board such that the substrate board of the electro-luminescence device is highly transparent to light, and flexible in addition to having a low permeability to moisture and oxygen.
A third object of this invention is to provide an organic electro-luminescence device having a metallocene based cyclic olefin copolymer substrate board and protective layer such that, in addition to providing a substrate board and protective layer having a high light transparency, flexibility and a low permeability to moisture and oxygen, the substrate board and the protective layer also have higher adhesive strength and a lower coefficient of thermal expansion (CTE).
To achieve these and other advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, the invention provides an organic electro-luminescence device. The organic electro-luminescence device comprises a substrate board, a cathode, a light-emitting layer, an anode and a protective layer. The cathode is configured over the substrate board and the light-emitting layer is configured over the cathode. The anode is configured over the light-emitting layer and the protective layer is configured around the substrate board and the anode as well as around the light-emitting layer and the cathode. The protective layer is made from a metallocene based cyclic olefin copolymer.
This invention also provides a second type of organic electro-luminescence device. The organic electro-luminescence device comprises a substrate board, a cathode, a light-emitting layer, an anode and a protective layer. The cathode is configured over the substrate board and the light-emitting layer is configured over the cathode. The anode is configured over the light-emitting layer and the protective layer is configured around the substrate board and the anode as well as around the light-emitting layer and the cathode. The substrate board is made from a metallocene based cyclic olefin copolymer.
This invention also provides a third type of organic electro-luminescence device. The organic electro-luminescence device comprises a substrate board, a cathode, a light-emitting layer, an anode and a protective layer. The cathode is configured over the substrate board and the light-emitting layer is configured over the cathode. The anode is configured over the light-emitting layer and the protective layer is configured around the substrate board and the anode as well as around the light-emitting layer and the cathode. Both the protective layer and the substrate board are made from a metallocene based cyclic olefin copolymer.
In this invention, a metallocene based cyclic olefin copolymer is used to form the protection layer. Thus, the protective layer has a high light transparency and a low permeability to moisture and oxygen. Aside from the protective properties, the protective layer is also an effective medium for dissipating light from a reflective anode emitting (top section emitting) type of organic electro-luminescence device.
The metallocene based cyclic olefin copolymer may also be used to form the substrate board of an organic electro-luminescence device. The substrate board is flexible in addition to having a high light transparency and relatively impermeable to moisture and oxygen. Thus, the substrate board has ideal properties as a component for a light penetrating and anode emitting (bottom section emitting) type of organic electro-luminescence device.
In addition, the metallocene based cyclic olefin copolymer may also be used to form both the substrate board and the protective layer of an organic electro-luminescence device. Aside from having a high light transparency and flexibility and a low permeability to moisture and oxygen and high flexibility, the substrate board and the protective layer also have a higher adhesive strength and a lower coefficient of thermal expansion.
It is to be understood that both the foregoing general description and the following detailed description are exemplary, and are intended to provide further explanation of the invention as claimed.